Shielding system for vapor-converters.



L. W. CHUBB. SHIELDING SYSTEM FOR VAPOR CONVERTERS. APPLICATION FILED Aus.9. I915.

197mm Patentedluly 16,1918,

WITNESSES 2 INVENTOR a fiw/fi Zen/4 W [/rufik ATTORNEY LEWIS w. 03mm, or EDGEWOOD PARK, PENNSYLVANIA, ssrcNon 'ro wnsrme- HOUSE ELEc'rmc AND mANurAc'rtmrNe COMPANY, A CORPORATION 01? PENN- SYLVANIA.

Specification of Letters Patent.

SHIELDING SYSTEM FOR VAPOR-CONVERTERS.

Patented July 16, acre.

' To all whom it may concern:

-Be it known that I, LEWIS W. CHUBB, a citizen of the United States, and a resident of Edgewood Park, in the county of Alleghen'y and State of Pennsylvania, have invented a new and useful Improvement in Shielding Systems for Vapor-Converters, of

whichthe following is a specification.

My invention relates to shielding systems for vapor converters, and it has for its ob- Y ject to provide means and apparatus whererarily negative, by a stream of electrons emitted from the latter and impinging upon the former.

The anodes employed in vapor converters are generally solld in nature, being formed of some refractory impervious material,

such, for example, as steel. In the manu facture of the converter, it is customary to treat out the interior of the container in order to remove the occluded gases from the material thereof. It has been found substantially impossible to remove the occluded gases from all portions of an anode of the character indicated, there being a strong tendency of the treating out are to concentrate upon the more exposed portions, leaving the less exposed portions with a certain amount of occluded gases. By my invention, I provide means whereby, in the normal operation of a converter, said electron stream is controlled, and the power are is therefore maintained upon portions of I ably the anodes which have been treated out, and the liberation of occluded gases is therefore reduced to a minimum.

Referring to the accompanying drawing for a more detailed understanding of my invention, I show the container of a vapor converter of the metal-case type at 1. Said container is provided with a pair of solid anodes 2 and 3 and with a cathode 4, preferformed of vaporizable reconstructing materiahsuch, for example, as mercury or suitable amalgams. The anodes 2 and 3 are connected, respectively, to the terminals of an alternating-current source 5, and the cathode 4 is connected to the mid point of the source 5 through a load 6, as is usual in the rectifier art. The cathode 4 is maintained in an active position by an suitable means, such, for example, as a esp-alive circuit 7, and the interior of the container 1 is highly exhausted. Each of the anodes 2 and. 3 may be provided with suppressor shields 8 and 9 of the type shown and claimed in a copending application of S. W.

Farnsworth, Serial No. 44,429, filed Aug. 9,

1915, and assigned to the Westinghouse Electric & Manufacturing Company.

Briefly speaking, the suppressor shields 8 and 9 comprise cylindrical casings surroundingthe anodes and provided with transverse diaphragms in the lower portions thereof, said diaphragms supporting a plurality of conducting insulated tubular members 1010. The tubular members 10-10 are connected to their associated anodes through resistance members 1111 so that each tubular member reverses in polarity with its associated anode and thus tends to suppress reversal of the arc stream by the creation of space charges. I provide a cylindrical conducting member 12 within each of the shielding systems 8 and 9, and I connect the member 12 associated with each anode to the other anode, preferably including one of the resistance members 11 in the connection so as to eliminate the possibility of short circuits. The cylindrical members 12 preferably terminate somewhat above the active portions of the anodes 2 and 3.

Having thus described the structure of a vapor converter embodying my invention,

the operation is as follows: When the anode 2 is temporarily positive with respect to the cathode 4, a power are passes therebetween, conveyed mainly by means of a stream of electrons emitted by the cathode and impinging upon the anode. The lower portion of the anode 2 is the only part thereof that can be effectively freed from occluded gases in the treating-out process and it is accordingly desirable that the power arc be restricted thereto. The anode 3 being charged negatively when the anode 2 is positive, a negative charge will be imparted to the shield 12 associated with the anode 2. and any electrons proceeding from the cathode 4 and tending to impinge upon the upper portion of the anode 2 will be repelled by the shield 12 associated therewith. The power are will therefore be maintained within the desired limits.

In like manner, in a succeeding half cycle, the power are proceeds to the anode 3, and the shield 12 thereof is negatively charged by reason of its connection to the anode 2, resulting in the repulsion of all electrons tending to impinge upon untreated portions of the anode 3.

The impact of an electron with a molecule of residual gas in the arc path fractures said molecule and produces an additional electron and a residual positive ion of. relatively large mass. There is a tendency for said positive ions to collect in the interior of a container and, if in sufficient number, their attraction to and bombardment of an anode when temporarily negative may break down the negative electrode reluctance thereof and cause short circuiting of the device.

Said harmful phenomenon is largely prevented in my apparatus by the following actions. In the first place, positive ions generated outside the main shields are neutralized thereby before they can reach the anodes, in the manner set forth in the aforementioned Farnsworth application. Positive ions generated within a main shield, when the associated anode is positive in potential, are drawn to, and neutralized by, the shield 12 and, when said anode is negative, said ions are repelled from the neighborhood thereof by the positive charge then existing on the shield 1 I have, for simplicity, limited the above discussion to are establishment and maintenance in the usual manner by means of a negative electron stream proceeding from the cathode to the anode, but, obviously, a similar shielding system could be applied to a cathode to control the locus of impact of a positive ion stream proceeding from an anode to said cathode.

Throughout this description, I have explained the action of my device in accordance with the theory which seems most plausible in view of the present knowledge of the underlying phenomena. I desire it to be distinctly understood however that I do not confine myself to said theory of operation but merely present the same to aid in an understanding of the invention.

While I have shown my invention in its preferred form, it will be obvious to those skilled in the art that it is susceptible of various minor changes and modifications without departing from the spirit thereof and I desire, therefore, that only such limitations shall be imposed thereupon as are impose by the prior art or are specifically set forth in the appended claims.

I claim as my invention: 1. In an evacuated electric device, the combination with a palr of electrodes, of

means for initiating and maintaining an arc therebetween, and means operative through electrostatic action for restricting said are to a portion only of one of said electrodes.

2. In an evacuated electric device, the com bination with a pair of electrodes, one of which is solid and has occluded gases liberated from but a portion thereof, of means for initiating and maintaining an are between said electrodes, and means operative through electrostatic action, for confining said are to the gasfree portion of said solid electrode.

3. In an evacuated electric device, the combination with a pair of electrodes, of means for initiating and maintaining an arc therebetween, and a conducting shield associated with a portion of one of said electrodes and electrostatically charged to prevent the flow of said arc to said portion of -combination with a pair of electrodes, one

of which is solid and has occluded gases liberated from but a portion thereof, of means for initiating and maintaining an are between said electrodes, a conducting'shield associated with the gas-bearing portion of said solid electrode, and means for charging said shield to a polarity opposite to that of said electrode when said are tends to flow between said electrodes, whereby the ions tending to produce said are How are substantially prevented from impinging upon said gas-bearing portions of said electrode.

6. In a vapor converter, the combination with a pair of anodes, of a cathode, a source of alternating current, a connection from one terminal of said source to one of said anodes and from the other terminal of said source to the remaining anode, a connection from said cathode to an intermediate point in said source, a conducting shield associated with each of said anodes, and a conductive connection including a current-limiting device between each shield and the other anode, whereby the impingement of negative electrons from said cathode upon said anodes is controlled.

7. In a vapor converter, the combination with a pair of anodes and a cathode, of means for causing said anodes to alternate in potential from a point above to a point below the potential of said cathode and for causing current to flow from either of said anodes to said cathode when said anode is positive with respect to said cathode, and a conducting shield associated with each anode and conductively connected to the other anode through acurrent-limiting device, whereby the flow of negative electrons from thelcathode to each anode is subject to contro 8. In a vapor converter, the combination with a pair of anodes and a cathode, each of said anodes comprising gas-freed and gasbearing portions, of means for causing said anodes to alternate in potential from a ointabove to a point below the potential 0 said cathode and for causing current to flow from either of said anodes to said cathode when said anode is positive with respect to said consequently, of the arc, to said gas-bearing portions is prevented.

9. In a vapor converter, the combination with a pair of anodes alternating in potential, of a cathode, perforated suppressor shields associated with each of said anodes and electrically connected thereto through current-limiting devices, an auxiliary conducting shield associated with each anode, and connections fromeach auxiliary shield to the other anode, whereby the movement of electrons to each anode is controlled.

10. In a vapor converter, the combination with a pair of anodes alternating in potential, each of said anodes having gas-free and gas-bearing portions, of a cathode, perforated suppressor shields associated with each of said anodes and electrically connected thereto through current-limiting devices, an auxiliary conducting shield associated with each' anode, and connections auxiliary shield to the other anode, whereby the movement of electrons to said gas-bearing portions and the consequent liberation of gas therefrom is substantially prevented.

In testimony whereof, I have hereunto subscribed my name this 31st day of July,

LEWIS W. CHUBB.

from each 

